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  Motor/encoder assembly for tape drivesUSPTO Application #: 20060202574Title: Motor/encoder assembly for tape drives Abstract: A magnetic/encoder assembly has a compact design and combines the features of motor, encoder and chuck locating feature within a single motor housing. The motor/encoder includes a DC brushless motor with an inner magnetic rotor. The motor windings and the commutation electronics are mounted towards the bottom side of a printed circuit board. The rotor of the motor is extended above the surface of the printed circuit board. The extended rotor provides a precision seat for the magnetic wheel with multiple poles. The top surface of the printed circuit board mounts the sensor for the encoder. The extension of the rotor provides the precision mounting surface of the cartridge driving chuck. (end of abstract) Agent: Mark Spolyar, Esq. Spolyar Technology Law Group - San Francisco, CA, US Inventors: Ashok B. Nayak, Robert R. Heinze USPTO Applicaton #: 20060202574 - Class: 31006800B (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20060202574. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] The present invention relates to the field of tape drives, and more particularly, to a motor/encoder system for a magnetic tape drive. BACKGROUND OF THE INVENTION [0002] In tape drive systems that utilize a single tape cartridge reel, once the cartridge is loaded and is registered at the appropriate datum, the tooth ring coupling of the cartridge reel becomes engaged with the motor system of the tape drive. The lead end of the tape, which is called the leader block or leader pin, is then transferred from the cartridge reel to the take up reel located inside the tape drive. This take up reel is also attached to a motor system. Once a leader pin has been successfully moved to the take up reel, the tape is located against the magnetic head of the tape drive and both of the reels of the tape drive are ready to be rotated by the motor/encoder, to start the read/write process. [0003] The motor/encoder system of a tape drive may have a number of functions, depending on the design of the tape drive. For example, the motor/encoder system can control the tape speed, regulate tape tension and align the take-up reel at a precise location to properly receive the leader pin. [0004] As the form-factor requirement of single reel cartridge tape drives decreases, the size of the components used to create the tape drive also diminish. Recent tape drives the use LTO cartridges have a form factor requirement of 51/4 inch. One of the requirements of this form factor is that the entire tape drive must fit into a height of 31/4 inch. Therefore, the motor/encoder system must also be designed to fit and properly function in a very limited space. [0005] Motor/encoder systems for precisely controlling the motor speed are known. In many such systems, the motor and the encoder are separate, individual components. The problem with this type of design is the space required to accommodate two separate parts; the motor and the encoder. In a tape drive system with a form-factor requirement, there is no space available for two separate motor and encoder components. Furthermore, providing two separate components normally have a higher cost in comparison to provision of a single component having dual functionality. It also adds assembly time and added cost of inventory. [0006] Another concern of certain encoding arrangements arises because of the use of a magnetic shaft encoder that employs a gear or a toothed wheel for inducing periodic electrical pulses in an inductive pick-up. The teeth of the wheel are evenly spaced and every tooth generates a signal as it passes the pick-up. One problem with such an encoder is its relatively limited resolution. This is because the size of the tooth is limited in how small the tooth can be made. In other arrangements, a magnetic code wheel is employed. Such arrangements use an inductive coil concept or a moving coil, movable together with a rotor, that interacts with the magnetic code wheel. A major concern with such an application is routing of the wire from the movable coil mounted at the center of the rotor. It requires a rotary shaft having a through hole formed along the axis of rotation of the motor's shaft to route the coil lead wires. [0007] There is a need for an arrangement in which the motor/encoder system is packaged in the smallest practical volume, yet provide the functions of housing a DC brushless motor with its driver circuitry, a magnetic encoder with necessary sensors and provide precision mounting and locating features for a cartridge driver component. SUMMARY OF THE INVENTION [0008] These and other needs are met by embodiments of the present invention which provide a tape drive comprising a rotor compartment, and means housed within the rotor compartment for coupling a rotor to a tape cartridge, rotating a tape cartridge reel, and encoding a position of the rotor. In certain embodiments of the invention, a magnetic code wheel is attached to the rotor that is rotatably mounted within the motor compartment. A magnetic code wheel sensor is stationarily positioned within the rotor compartment, which senses rotation of the magnetic code wheel. The invention thus improves upon the current limited resolution offered by devices which employ a toothed ring gear and inductive pick-up. Since all three functions are housed within a single rotor (or motor) compartment, a compact design can be provided. [0009] The earlier stated needs are also met by other embodiments of the present invention which provide a motor/encoder assembly for a tape drive, comprising a motor housing and a DC motor mounted in the housing. The DC motor has a rotor, a field magnet attached to the motor, motor laminations and windings. A code wheel is mounted on the rotor within the motor housing. A code wheel sensor is fixedly mounted within the motor housing. A chuck mounting element is provided on the rotor. [0010] The earlier stated needs are also met by another aspect of the present invention which provides a tape drive with a motor/encoder assembly comprising a motor housing, a DC brushless motor with driver circuits located entirely within the housing, and an encoder with encoder sensors located entirely within the motor housing. The tape cartridge driver is mounted on the DC brushless motor. [0011] The foregoing and other features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0012] FIG. 1 is a perspective view of a tape transport mechanism constructed in accordance with embodiments of the present invention. [0013] FIG. 2 depicts a perspective view of a LTO single reel cartridge usable with the tape drive of the present invention. [0014] FIG. 3 depicts a bottom view of the tape transport in accordance with embodiments of the present invention. [0015] FIG. 4 shows the tape transport of FIG. 1, but with the cartridge loader removed for illustrative purposes. [0016] FIG. 5 shows a schematic depiction of a cross-section of the motor/encoder system using a magnetic encoder, constructed in accordance with embodiments of the present invention. [0017] FIG. 6 shows an assembled motor/encoder system constructed in accordance with embodiments of the present invention. [0018] FIG. 7 shows the motor/encoder system of FIG. 6 in an exploded view. [0019] FIG. 8 shows a magnetic code wheel assembly constructed in accordance with an embodiment of the present invention. [0020] FIG. 9 shows a top perspective view of a motor/encoder assembly constructed in accordance with an embodiment of the present invention in which an optical encoder is employed instead of a magnetic code wheel. Continue reading... Full patent description for Motor/encoder assembly for tape drives Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Motor/encoder assembly for tape drives patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. 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